JP2003227470A - Pump device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To cope with various kinds of liquid different in specific gravity with uniform specifications, while operating a pump by utilizing a current capacity of a motor part to a maximum extent. <P>SOLUTION: In this pump device comprising a pump part 10, the motor part 12 and a frequency converter 14 for supplying the power to the motor part 12, the relationship between an output frequency of the frequency converter 14 and the output voltage is uniquely determined in advance, a rotating speed of the pump is controlled to make a current value of the motor part 12 be constant, and an upper limit value and a lower limit value of the output frequency and determined to limit a control range of the rotating speed of the pump. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump device,
In particular, a pump section, a motor section for driving the pump section,
A frequency converter for supplying power to the motor section is provided, and while operating the pump making maximum use of the current capacity of the motor section,
The present invention relates to a pump device that can be applied to arbitrary handled liquids having different specific gravities with the same specifications.

[0002]

2. Description of the Related Art Conventionally, if a pump device designed for water, for example, is directly applied to a handling liquid having a larger specific gravity than water, the pump output may exceed the rated value. Therefore, when handling an arbitrary handling liquid having a different specific gravity, it is necessary to separately prepare and use a pump device having a motor having an output corresponding to the specific gravity of the handling liquid.

Further, a frequency converter represented by an inverter is provided, and the power supply frequency and voltage are changed by using this frequency converter to control the rotational speed of the pump so that the pump output falls within the rated value. Is also known.
In the pump device including such a frequency converter, when the specific gravity of the handled liquid is different, it is necessary to individually reset the operating frequency according to the specific gravity of the treated liquid.

[0004]

However, when handling various handling liquids having different specific gravities as in the above-mentioned conventional example,
If you separately prepare and use a pump device that combines a motor unit and a pump unit that have an output that matches the specific gravity of the handled liquid, you will need multiple types of pump specifications, resulting in poor productivity and usability. there were. Even in a pump device using a frequency converter, if the specific gravity of the handled liquid changes, it is necessary to reset the operating frequency according to the specific gravity of the handled liquid, and there is a similar problem.

The present invention has been made in view of the above, and it is possible to operate a pump that makes maximum use of the current capacity of a motor section and, at the same time, respond to arbitrary liquids with different specific gravities with the same specifications. The purpose is to provide a device.

[0006]

According to a first aspect of the present invention, there is provided a pump device comprising a pump section, a motor section for driving the pump section, and a frequency converter for supplying electric power to the motor section. The relationship between the output frequency and the output voltage of the converter is uniquely determined in advance, and the rotation speed of the pump is controlled so that the current value of the motor section becomes constant, and the upper and lower limits of the output frequency are set. The pump device is characterized by setting a value to limit a control range of the rotation speed of the pump.

As described above, the output frequency of the frequency converter is controlled so that the current value of the motor section becomes constant irrespective of the operating head and flow rate of the pump, so that the current capacity of the motor section can be utilized to the maximum extent. It is possible to operate the pump. Moreover, the output frequency of the frequency converter has the maximum value (upper limit frequency).
The provision of this prevents the rotation speed of the pump from increasing beyond the limit value when applied to a handling liquid with a relatively small specific gravity or when air is mixed in the handling liquid, and it also prevents the output frequency of the frequency converter from increasing. By setting a minimum value (lower limit frequency) in the above, it is possible to prevent the rotation speed of the motor part from excessively decreasing and causing resonance between the pump part and the motor part when applied to a handling liquid with a relatively large specific gravity. It is possible to prevent the rotational speed of the pump from decreasing indefinitely when the pump is in the overloaded state and the detection of the overloaded state from becoming impossible.

According to a second aspect of the present invention, the lower limit value of the output frequency of the frequency converter is set to approximately 5 times the upper limit value of the output frequency.
The pump device according to claim 1, wherein the pump device is set to 0%. Generally, in a pump device of a small to medium output class which is frequently used in a semiconductor manufacturing factory or the like, when the pump device is operated at a frequency of 50% or less of an upper limit (rated) frequency, the pump part and the motor part resonate with each other, causing a large vibration. However, by setting the lower limit value of the output frequency of the frequency converter to about 50% of the upper limit value of the output frequency in this way, the frequency can be reduced when applied to a handling liquid having a relatively large specific gravity. It is possible to avoid the risk of the pump portion and the motor portion resonating due to excessive reduction.

According to a third aspect of the present invention, in the pump device according to the first or second aspect, the frequency converter is provided with a changeover switch that changes the current value of the motor section in a stepwise manner. is there. This makes it possible to easily perform the stepwise switching of the target current value of the motor section through the changeover switch provided in the frequency converter.

According to a fourth aspect of the present invention, the relationship V / F between the output frequency F and the output voltage V of the frequency converter is constant, and the current value of the motor section is approximately 5 with the minimum value being the maximum value.
The pump device according to claim 3, wherein the pump device is set to 0%.

Thus, the output frequency F of the frequency converter is
When the rotation speed of the motor unit is controlled so that the current value of the motor unit becomes constant while the relation V / F between the output voltage V and the output voltage V is constant, the torque of the motor unit is almost constant regardless of the rotation speed of the pump. Therefore, the output of the motor section is proportional to the rotational speed of the pump because the current is constant and the voltage changes in proportion to the rotational speed. Therefore, by controlling the output frequency of the frequency converter so as to keep the current value of the motor constant regardless of the operating head and flow rate of the pump, it is possible to operate the pump by maximizing the current capacity of the motor. It will be possible. Moreover, by setting the minimum value of the current value of the motor part to about 50% of the maximum value, even if the current resolution of the device is taken into consideration, several set current values can be provided between them. .

The invention according to claim 5 is the pump device according to any one of claims 1 to 4, characterized in that the respective pump characteristics when applied to a plurality of handling liquids having different specific gravities are displayed. is there. Thereby, each pump characteristic when applied to a plurality of handling liquids having different specific gravities can be visually confirmed.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a pump device according to an embodiment of the present invention applied to a full-circulation canned motor pump. This pump device (full-circle canned motor pump)
Is mainly composed of a pump unit 10, a motor unit 12 that drives the pump unit 10, and a frequency converter 14 that supplies power to the motor unit 12.

The pump portion 10 has a suction side casing 18 which houses an impeller 16 therein, a discharge side casing 20 which is arranged on the opposite side of the suction side casing 18 with the motor portion 12 interposed therebetween, and a motor frame described below. An outer casing 24 is provided on the outer periphery of the outer casing 28 and forms an annular space 22 connecting the suction side casing 18 and the discharge side casing 20 with the motor frame 28. A suction side casing 18 and a discharge side casing 20 made of stainless cast steel or the like are fixed to both axial ends of the outer casing 24 via O-rings 25, 25. These are formed by the lost wax casting method using, for example, stainless cast steel.

The motor section 12 has a motor frame 28 in which a stator 26 is fixedly housed by shrink fitting or the like, and a motor frame side plate 30 is hermetically welded to an axially open end of the motor frame 28. There is. Stator 2
A stator can 32 made of a stainless steel thin plate or the like is fitted to the inner peripheral portion of 6, and the stator can 32 is hermetically welded to the motor frame 28 and the motor frame side plate 30.

A rotor 34 is rotatably housed inside the stator 26. The rotor 34 is fixed to the main shaft 36 by shrink fitting, and the rotor can 38 and the rotor side plate 4 are
The rotor 34 is protected from corrosion by the handling liquid by sealingly welding the shafts 0, 40 and the rotor side plates 40, 40 and the main shaft 36. The rotor can 38 and the rotor side plate 4
The material of 0, 40 and the main shaft 36 is, for example, stainless steel. The main shaft 36 has a motor frame 28 at both ends.
The impeller 16 is fixed to one end of the main shaft 36, and is supported by bearings installed on the motor frame side plate 30. The impeller 16 is a cast molded product made of, for example, stainless cast steel.

A radial bearing 44 and a fixed thrust bearing 46 are provided on the bearing bracket 42 in the peripheral portion of the non-impeller side bearing. The end surface of the radial bearing 44 also has a function as a fixed-side thrust bearing that supports a reverse thrust load that is rarely generated. On both sides of the radial bearing 44 and the fixed thrust bearing 46, there are provided a rotating forward thrust bearing 48 for supporting a forward thrust load and a rotating reverse thrust bearing 50 for supporting a reverse thrust load. There is. Two thrust bearings 48, 50
Are shrink-fitted and fixed to the thrust discs 52 and 54, respectively, and the two thrust discs 52 and 54 sandwich the sleeve 56 which constitutes the radial bearing and the sliding portion,
It is fixed by a double nut 58 provided at the end of the main shaft 36.

The bearing bracket 42 is in contact with the motor frame side plate 30 via an O-ring 60 made of an elastic material. The materials of the thrust bearings 46, 48, 50, the radial bearing 44 and the sleeve 56 are, for example, one kind of ceramic, SiC, and the materials of the bearing bracket 42 and the thrust disks 52, 54 are, for example, stainless steel.

A radial bearing 64 is provided on the bearing bracket 62 around the impeller-side bearing, and is inserted into the motor frame 28 via an O-ring 66 made of an elastic material. The radial bearing 64 and the sleeve 68 forming a sliding portion are fixed by a nut 72 provided at an end of the main shaft 36 via a washer 70 and an impeller 16.

The frequency converter 14 is a frequency converter main body 8
0 and a case 82 that divides the frequency converter main body 80 in a hermetically sealed manner. The case 82 is attached to a flat seat 24 a provided on the outer casing 24. The frequency converter main body 80 is connected to the power cable 84 as a means for inputting electric power from the power source, and the output of the frequency converter main body 80 is supplied to the stator 26 of the motor unit 12 via the lead wire 86. It Furthermore,
The case 82 is connected to the frequency converter body 80,
A changeover switch (current setting device) 88 for changing the current value of the motor unit 12 in stages is attached.

Although not shown, the frequency converter 14 includes a current value detecting means for detecting the current value of the motor section 12, and a comparator for comparing the detected current value detected with a preset current value. Is provided.

The frequency converter 14 converts the frequency and voltage of the AC commercial power source on the primary side and outputs it to the secondary side. The relationship between the output frequency F and the output voltage V is uniquely determined in advance. ing. That is, for example, the relationship V / F or V / F ² between the output frequency F and the output voltage V is set to be constant. Therefore, when the frequency converter 14 is supplied with a signal of a certain frequency, the frequency converter 14 supplies the frequency F and the voltage V proportional to this frequency or the square root of this frequency to the motor unit 12. There is.

From the frequency converter 14 to the motor unit 1
If the value of the ratio of voltage / frequency (V / F) supplied to 2 is set to a constant value, the torque of the three-phase induction motor is basically determined by the current flowing in the motor section, and the current value of the motor section is kept constant. When the rotational speed of the pump is controlled as described above, the motor torque becomes almost constant regardless of the rotational speed of the pump. The output of the motor unit is proportional to the rotation speed of the pump because the voltage V changes in proportion to the rotation speed with a constant current value. Therefore, the current capacity of the motor unit 12 is maximized by controlling the output frequency F of the frequency converter 14 so as to keep the current value of the motor unit 12 constant regardless of the operating head and flow rate of the pump. The pump can be operated.

In order to carry out such an operation, the current on the secondary side of the frequency converter 14, that is, the current of the motor section 12 is detected by the current detector, converted into an instrumentation signal by the current converter, and then the comparator. To enter. On the other hand, the allowable current of the motor unit 12 in the expected frequency range is preset. Then, the comparator amplifies and outputs the deviation between the set current value and the current value of the motor unit 12. In the frequency signal generator, the output frequency F on the secondary side of the frequency converter 14 is set as a simple feedback system so that the deviation between the set value and the detected value approaches zero.
Is changed to supply power to the motor unit 12.

With such a feedback control system,
The frequency F supplied to the motor unit 12 is always the motor unit 1
2 is adjusted so that it is operated at a constant allowable current value.
That is, when the flow rate is small, the current value of the motor unit 12 decreases, so that the frequency F increases and the rotation speed increases so as to approach a constant current value, and since V / F = constant, the voltage increases, The current value rises to the set value. At high flow rate,
Since the current value increases, the frequency F decreases so as to approach the constant current value, the rotation speed decreases, and V / F = constant, so the voltage value decreases and the required power decreases.

Here, in this example, the upper limit value (upper limit frequency) and the lower limit value (lower limit frequency) of the output frequency F of the frequency converter 14 are set to limit the control range of the rotational speed of the pump. While operating the pump making maximum use of the current capacity of the motor unit 12, it is possible to handle arbitrary handled liquids having different specific gravities with the same specifications.

That is, as described above, when the output frequency F of the frequency converter 14 is controlled so that the current value of the motor section 12 becomes constant, the present invention can be applied to a handling liquid having a relatively low specific gravity or to a handling liquid. When air is mixed, the rotation speed of the pump increases beyond the limit value, or when it is applied to a handling liquid with a relatively large specific gravity, the rotation speed of the pump decreases excessively and the pump and motor parts Resonance may be caused, or if the pump becomes overloaded, the rotational speed of the pump may decrease indefinitely, making it impossible to detect the overloaded condition. By setting the upper limit value and the lower limit value of the output frequency F and limiting the control range of the rotation speed of the pump, such an adverse effect is prevented.

Here, the frequency converter 1 is attached to the motor section 12 of the pump device adapted to be applied to the handled liquid having a specific gravity of 1-2.
The upper limit value and the lower limit value of the output frequency F supplied from No. 4 are suitable for the specific gravity of the handled liquid. Note that, here, a case will be described in which the relationship V / F between the output frequency F and the output voltage V of the frequency converter 14 is fixed, and the current value of the motor unit 12 is 50% of the minimum value of the current value.

Output frequency F and output voltage V of the frequency converter
When the relationship of V / F is constant, the output current (current value of the motor section) is I, the pump output is L, the pump discharge pressure is P,
When the specific gravity is γ, there is a relationship of V∝F ………… L ∝γF ³ ………… L ∝VI ………… P ∝γF ² ……. Now, output frequency F = 1 (100%),
When the specific gravity γ = 1, V = L = I = P = 1 and V = F = x
_Set to ₀ .

In this state, if the output current (motor current value) I = 1 is maintained and the specific gravity is γ = 2, then V = F = x ₁ , L = 2x ₁ ³ = x ₁ × 1 and x ₁ = 1 / √2 = 0.71, ∴F≈0.71. Next, assuming that the output current (current value of the motor portion) I = 0.5 with the specific gravity γ = 1, V = F = x ₂ , L = x ₂ ³ = x ₂ x0.5, so x ₂ = 1 / √2 = 0.71, ∴F≈0.71. Furthermore, the output current (current value of the motor section) I = 0.
5, given a specific gravity γ = 2, V = F = x ₃ and L = 2x ₃ ³ = x ₃ × 0.5, so x ₃ = 0.5, ∴F≈0.5.

As a result, the applicable range of the specific gravity of the handled liquid is 1
2 to 2, the ratio of the current value I of the motor unit 12 and the ratio of the operating frequency (output frequency of the frequency converter) F is as shown in FIG.
As shown in. That is, the current value I of the motor unit 12 =
The operating frequency (output frequency of the frequency converter) F at 1 (100%) decreases along the line a connecting x ₀ and x _1, and the current value I of the motor unit 12 is 0.5 (50). %), The operating frequency (output frequency of the frequency converter) F decreases along the line b connecting x ₂ and x ₃ .

Thus, the applicable range of the specific gravity of the handled liquid is 1
If it is set to 2, the high specific gravity liquids that are frequently used in semiconductor factories belong to this range, and if the minimum set current value is suppressed to about 50% of the maximum set current value, the decrease of the operating frequency becomes the upper limit (rated value). ) It can be suppressed to about 50% of the frequency.

Further, normally, if the minimum set current value can be lowered to about 50% of the maximum set current value, even if the current resolution of the equipment is taken into consideration, several set current values should be provided between them. You can For example, 2.2kW class (200
The motor rated current value of V) is about 12A, and if the maximum set current value is 12A and the minimum set current value is 6A, even if the interval of each set current value is 1A considering the current resolution, A set current value of 5 steps can be provided on the way.

Next, the pump device having the operating frequency (output frequency of the frequency converter) set in this way is set to a specific gravity γ.
Fig. 3 shows the relationship among the discharge pressure, the discharge amount, the motor current value, and the operating frequency when applied to the handling liquid of = 1.0. In FIG. 3, c ₁ and d ₁ show the case of operating at the upper limit frequency, and e ₁ and f ₁ show the case of operating at the lower limit frequency.

From this figure, when applied to a handling liquid having a relatively small specific gravity and the current value of the motor section is set high, in the region where the discharge amount is large, it follows the original operating frequency. In the region where the discharge amount is small, the discharge amount is small, but the discharge amount is small, and the discharge amount is smaller than the rated value.

In addition, such a pump device has a specific gravity γ =
Discharge pressure, discharge amount when applied to the handling liquid of 1.8,
FIG. 4 shows the relationship between the current value of the motor section and the operating frequency.
In FIG. 4, c ₂ and d ₂ show the case of operating at the upper limit frequency, and e ₂ and f ₂ show the case of operating at the lower limit frequency.

From this figure, when applied to a handling liquid having a relatively large specific gravity and the current value of the motor section is set low, in the region where the discharge amount is small, it follows the original operating frequency. In the region where the pump is operated but the discharge amount is large, the pump is operated along the lower limit frequency, which can eliminate the possibility that the frequency is excessively reduced and the pump section and the motor section cause resonance.

[0038]

As described above, according to the present invention,
While operating the pump making maximum use of the current capacity of the motor part, it is possible to handle arbitrary handled liquids with different specific gravities with the pump device of the same specification, thereby improving productivity and The usability can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a pump device according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the operating frequency and the specific gravity when the current values of the motor section are 100% and 50%.

[Figure 3] Handling liquid with relatively small specific gravity (specific gravity γ = 1.0)
6 is a graph showing the relationship among the discharge pressure, the discharge amount, the current value of the motor unit, and the operating frequency of the pump device applied to FIG.

[Fig. 4] Handling liquid with relatively large specific gravity (specific gravity γ = 1.8)
6 is a graph showing the relationship among the discharge pressure, the discharge amount, the current value of the motor unit, and the operating frequency of the pump device applied to FIG.

[Explanation of symbols]

10 Pump section 12 Motor part 14 Frequency converter 16 impeller 22 Ring space 24 Outer casing 26 Stator 34 rotor 36 spindle 80 frequency converter body 82 cases 84 power cable 86 lead wire 88 changeover switch

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Riki Makino             11-1 Haneda Asahi-cho, Ota-ku, Tokyo Co., Ltd.             Inside the EBARA CORPORATION (72) Inventor Masakazu Komai             4-1-1 Honfujisawa, Fujisawa City, Kanagawa Prefecture             In ceremony company EBARA DENSAN (72) Inventor Hideki Hagino             4-1-1 Honfujisawa, Fujisawa City, Kanagawa Prefecture             In ceremony company EBARA DENSAN F term (reference) 3H045 AA06 AA08 AA12 AA22 BA31                       CA21 CA29 DA07 EA36

Claims (5)

[Claims] 1. A pump device comprising a pump section, a motor section for driving the pump section, and a frequency converter for supplying power to the motor section, wherein the relationship between the output frequency and the output voltage of the frequency converter is unique in advance. Control is performed to control the rotation speed of the pump so that the current value of the motor unit becomes constant, and the upper and lower limits of the output frequency are set to control the rotation speed of the pump. A pump device having a limited range. 2. The pump device according to claim 1, wherein the lower limit value of the output frequency of the frequency converter is set to approximately 50% of the upper limit value of the output frequency. 3. The pump device according to claim 1, wherein the frequency converter is provided with a changeover switch for changing over a current value of the motor section in a stepwise manner. 4. The current value of the motor unit is set such that the minimum value thereof is approximately 50% of the maximum value with the relationship V / F between the output frequency F and the output voltage V of the frequency converter being constant. The pump device according to claim 3. 5. The pump device according to claim 1, wherein each pump characteristic when being applied to a plurality of handling liquids having different specific gravities is displayed.